1. Field of the Invention
The present invention relates in general to ventilation air intake structures of a motor vehicle, and more particularly, to ventilation air intake structures of a type which can smoothly drain rainwater therefrom.
2. Description of the Prior Art o In order to clarify the task of the present invention, one of the conventional ventilation air intake structures will be described with reference to FIGS. 4 and 5 of the accompanying drawings, and which is described in Japanese Patent First Provisional Publication No. 59-23720.
It is to be noted that the structure shown in FIG. 4 is a view taken from a front corner position of the associated motor vehicle.
In the drawings, denoted by numeral 1 is an elongate air box which extends laterally along a rear upper edge portion of an engine room (not shown). The elongate air box 1 is defined by a cowl top panel 2, a dash upper panel 3 and two side panels 4 (only one is shown), which are combined to constitue an elongate air box chamber. Longitudinally opposed ends of the air box 1 are each connected to both a hood ridge reinforcing member 12 and a front pillar 6.
As is seen from FIG. 5, the cowl top panel 2 is formed with an air intake opening 2a, while, the dash upper panel 3 is formed with an opening 3a. The air intake opening 2a is used for introducing fresh air into the air box 1, while, the opening 3a is used for carrying the fresh air in the air box 1 toward a passenger cabin (not shown). An intake tube 40 extends from the opening 3a to the passenger cabin for achieving this air flow. From the periphery of the opening 3a of the dash upper panel 3, there is raised an annular wall 7 which is projected into the air box 1 to serve as a water stopper. Each side panel 4 and the dash upper panel 3 constitute a small passage 8 which is provided with a one-way valve 9. The valve 9 permits only a flow of water in the direction from the air box 1 toward a drain passage 10 which is defined by the hood ridge reinforcing member 12, the side panel 4 and the side end portion of the dash upper panel 3. The drain passage 10 has a drain opening 11 formed in the hood ridge reinforcing member 12. Thus, as is understood from FIG. 4, the drain passage 10 is exposed to the outside of the vehicle at the drain opening 11.
Thus, rainwater in the air box 1 is permitted to flow through the small passage 8, the one-way valve 9 and the drain passage 10 and finally drain into the outside through the drain opening 11.
However, due to its inherent construction, the above-mentioned conventional ventilation air intake structure has the following drawbacks.
First, because the bottom of the air box 1 and the drain opening 11 are arranged at substantially the same height, effective draining of water from the drain opening 11 is not achieved. Although the water draining is somewhat improved when the size of the drain opening 11 is enlarged, this measure lowers the mechanical strength of the hood ridge reinforcing member 12. Furthermore, the enlargement in size of the drain opening 11 causes lowering of not only the sound insulation effect but also the offensive odor shutting effect provided by a passage between the air box 1 and the drain opening 11. Furthermore, the enlargement of the drain opening 11 lowers the natural ventilation effected by the ram pressure produced when the vehicle is moving.
Second, if the drain opening 11 is reduced in size for eliminating the above-mentioned drawbacks, the water draining effect is lowered. Furthermore, in this case, undesired back flow of the water tends to occur in the passage between the air box 1 and the drain opening 11 particularly when the vehicle is moving and the air inlet opening 2a is covered with a foreign object, such as, snow and the like.